The process of paving roads, runways, parking areas and the like with asphaltic concrete (asphalt) involves the transportation of the asphalt from the manufacturing plant to the paving site. Numerous types of vehicles are employed to transport asphalt from the manufacturing plant to the paving site. These vehicles include tandem dump trucks, tri-axle dump trucks, dump trailers, live-bottom trailers, hopper trailers, center drop trailers, double trailers, and the like. The asphalt transported by these vehicles is received “hot” so that it is in a workable condition at the paving site. To prevent the asphalt from sticking or adhering to the bed of the transportation vehicle, a lubricating type material commonly known as asphalt release agent is applied to the truck bed prior to loading the asphalt.
The most common form of release agents are liquids which are sprayed or splashed or otherwise applied to the vehicle truck beds. One common method of spraying the truck bed with release agent is by the use of a pump-up sprayer. In such applications, a measure of release agent is placed into the tank of the pumping unit, diluted as required (typically with water), agitated, and then pressurized to a sufficient air pressure to spray the bed of the truck. The spraying is conducted by the vehicle operator or personnel at the asphalt plant controlling a wand or a nozzle to direct the flow of the spray unit. This method is somewhat ineffective in that the sprayers generally do not spray uniformally, and have decreasing air pressure while they are being used. Additionally, this method may require the vehicle operator or other personnel to climb up onto the truck bed, presenting obvious safety hazards.
Other conventional spray units operate in cooperation with a stand built to allow the driver or other personnel to be at truck bed level while applying the release agent. Spray units of this type may employ a pump or venturi (using water pressure, air pressure or both) to dilute the release agent and supply the necessary pressure to spray the diluted release agent through an appropriate nozzle. Such units also have numerous drawbacks, including the lack of control over the release agent concentration due to variability of water and/or air pressure, lack of uniformity of application, and time and safety risks associated with driver or personnel involvement in the application of the release agent.
Other pump type asphalt release agent applicators are available which require that the release agent be used neat or pre-diluted. The use of neat release agents is very expensive due to increased freight and handling costs. For example, to provide diluted release agent at a manufacturing site requires additional equipment both for transfer of the concentrate and the mixing process. Furthermore, the uniformity of the resulting mixture is often unsatisfactory.
Accordingly, there is a need for a system and method of applying release agent to the bed of transportation vehicles which does not require an operator to leave the vehicle, which recognizes the type of vehicle to which the agent is to be applied, which controls the amount and concentration of the release agent used, and effectively and efficiently sprays the bed of the vehicle.